General purpose dump trucks are conventionally constructed with a load-carrying bed mounted for tilting movement and a pivotally mounted tailgate closing the rear of the bed. In normal dump truck operation, the truck is moved to the location where the material is to be unloaded, and the forward end of the dump truck bed is raised. The operator then releases the tailgate of the dump truck bed so that the material gravitates out of the open rear end of the vehicle. Spreading of the material is then accomplished by moving the dump truck forward as the material is released.
In small, limited areas such as parking lots, driveways, cul-de-sacs, etc., it is difficult to spread the desired length and depth of material with a conventional dump truck. Once the tailgate is released, the only way to stop the flow of material before dumping all of the material retained within the truck is to lower the bed of the dump truck. The usual result is to scatter the material over a larger area, or to deposit uneven piles of material in the wrong places. Consequently, more equipment and/or labor is needed to distribute the dumped material at the desired location.
Heretofore, there have been several attempts to provide tailgate arrangements for varying or controlling the discharge rate of material from a dump truck. U.S. Pat. No. 3,361,475 discloses an auxiliary discharge control comprising a pivotally movable tailgate and a controllable chute therebelow for operator control of the rate of discharge. The chute is tilted rearward and forward thereby controlling the discharge of material from the truck. Other arrangements have included a tailgate construction adapted to provide a sealed truck bed for retaining bulk material disclosed in U.S. Pat. No. 1,952,833, then, when the tailgate was unlocked and lowered, the tailgate served as a dumping board. U.S. Pat. No. 1,735,930 teaches a tailgate arrangement comprising and end gate which could be suspended upright from its upper end and raised to discharge the load directly, or hinged at its lower end and dropped down so that the load would discharge therethrough when the body was tilted. Yet another arrangement disclosed in U.S. Pat. No. 2,248,374 comprised a windrowing gate which controlled and distributed the discharge of material, such as gravel, from the dump truck. Although useful to some degree, the aforesaid tailgate arrangements failed to provide sufficient variations and control of the discharge rate.
Therefore, a primary object of the present invention is to provide a controllable tailgate for a conventional dump truck, which provides superior control and variation of the discharge rate, thereby minimizing the need for subsequent labor and equipment to distribute material to the desired location and in the desired amount.
Another object of the present invention is to provide an auxiliary discharge control means for a dump truck which requires a minimum of operator intervention.
Another object of the present invention is to provide an auxiliary discharge control means for a dump truck which makes it possible to produce different widths of discharge.
Yet another object of the present invention is to provide an auxiliary discharge means which can be easily adapted to conventional dump truck load carrying bodies, without interfering with the normal operation of the dump truck.